To use the elimination method, you have to create variables that have the same coefficient, then you can eliminate them.
64 x 100 = 6400
11 x x = 11x
I’ll solve this out for you
11x = 6400
Divide 11 from both sides
x = 581.8
Hope this helps!
I don't know if you meant profit or markup but,
take the difference of $80 & $50 = $30
What percent of 50 is 30? It's 3/5 or 60%. So there is a 60% markup on the original price of 50$.